Question

I have a LINQ query with more than 2 where conditions, but it doesn’t seem to evaluate with more than 2 conditions. Is there a way to add more conditions to the where clause?

var query = 
   from f in XElement.Load(MapPath("flightdata3.xml")).Elements("flight")
   where (string)f.Element("departurelocation") == From && 
         (string)f.Element("destinationlocation") == DestCity &&
         (string)f.Element("airline") == Airline
         // && (string)f.Element("departuredate") == DepartDate && 
         // (string)f.Element("departuretime")==DepartTime
         //&& (string)f.Element("returndate")==ReturnDate && 
         //(string)f.Element("returntime")==ReturnTime
   orderby Convert.ToInt32(f.Element("price").Value)
   select new
   {
      FlightNumber = (Int32)f.Element("flightnumber"),
      Airline = (string)f.Element("airline"),
      Departure = (string)f.Element("departureairportsymbol"),
      DepartTime = (string)f.Element("departuretime"),
      Destination = (string)f.Element("destinationairportsymbol"),
      ArrivalTime = (string)f.Element("arrivaltime"),
      Stops = (int)f.Element("numberofstops"),
      Duration = (string)f.Element("duration"),
      Cabin = (string)f.Element("cabin"),
      Price = "$" + (Int32)f.Element("price"),
      ImagePath = (string)f.Element("airlineimageurl").Value
   };

Answer 1

LINQ absolutely allows more than two WHERE conditions. Have you tried separating the query into more manageable pieces? LINQ uses deferred execution anyway so you won’t see a performance penalty in doing so.

You should also consider making a class to hold the information you’re stuffing into the result.

public class FlightDetail
{
    public Int32 FlightNumber { get; set; }

    public String Airline { get; set; }

    public String Departure { get; set; }

    public String DepartureTime { get; set; }

    public String Destination { get; set; }

    public String ArrivalTime { get; set; }

    public Int32 Stops { get; set; }

    public String Duration { get; set; }

    public String Cabin { get; set; }

    public Int32 Price { get; set; }

    public String ImagePath { get; set; }
}

Then something like this which is more readable but should also help you find whatever bug is popping up.

var flights = 
   from f in XElement.Load(MapPath("flightdata3.xml")).Elements("flight")
   select new FlightDetail
   {
      FlightNumber = (Int32)f.Element("flightnumber"),
      Airline = (string)f.Element("airline"),
      Departure = (string)f.Element("departureairportsymbol"),
      DepartTime = (string)f.Element("departuretime"),
      Destination = (string)f.Element("destinationairportsymbol"),
      ArrivalTime = (string)f.Element("arrivaltime"),
      Stops = (int)f.Element("numberofstops"),
      Duration = (string)f.Element("duration"),
      Cabin = (string)f.Element("cabin"),
      Price = "$" + (Int32)f.Element("price"),
      ImagePath = (string)f.Element("airlineimageurl").Value
   };

var flightsByLocation = 
   flights.
   where (string)f.Element("departurelocation") == From && 
         (string)f.Element("destinationlocation") == DestCity
   select new FlightDetail
   {
      FlightNumber = (Int32)f.Element("flightnumber"),
      Airline = (string)f.Element("airline"),
      Departure = (string)f.Element("departureairportsymbol"),
      DepartTime = (string)f.Element("departuretime"),
      Destination = (string)f.Element("destinationairportsymbol"),
      ArrivalTime = (string)f.Element("arrivaltime"),
      Stops = (int)f.Element("numberofstops"),
      Duration = (string)f.Element("duration"),
      Cabin = (string)f.Element("cabin"),
      Price = "$" + (Int32)f.Element("price"),
      ImagePath = (string)f.Element("airlineimageurl").Value
   };